1. Percent of total breedings
Increased use of young bulls in dairy cattle breeding programs
H. D. Norman, J. L. Hutchison,* and J. B. Cole
Animal Improvement Programs Laboratory, Agricultural Research Center, USDA, Beltsville, MD
2012
Abstr. W60
INTRODUCTION
Breeding programs have changed since genomic evaluations became available in Breeders and producers are now making much heavier use of young bulls than in the past, which results in shorter generation intervals and increased selection intensity. The number of bulls has increased, which provides opportunities to sample more diverse pedigrees.
DISCUSSION
Generation interval
Age of sire for Holstein males born in 2011 was 23 months younger than males born in 2006, 15 months younger for Jersey males
Age of sire for Holstein females born in 2011 was 12 months younger than females born in 2006, 4 months younger for Jersey females
Sires of young AI bulls
Total number of sires of young bulls has doubled for Holsteins (126 in 2008 to 276 in 2011), nearly doubled for Jerseys (34 and 54)
Sons sired by young bulls
Increased 48 percentage points (13% in 2008 compared with 61% in 2011), 36 percentage points for Jerseys
Young bulls as service sires
Matings to young Holstein bulls have increased 20 percentage points (28% in 2007 compared with 48% in 2011), 15 percentage points for young Jersey bulls (25% compared with 40%)
Matings to genotyped young bulls have rapidly increased while non-genotyped young bulls are virtually not used with the onset of genomics
Female progeny sired by young bulls (not shown)
Young bulls annually sired 24, 23, 23, 33, and 40% of Holstein heifers born from 2007 through 2011 and 29, 27, 30, 33, and 35% of Jersey heifers
Genetic merit for genotyped vs. active bulls
Net merit differences were -$60, $144, and $171, for 2008, 2009, and 2010 for Holstein bulls, and $126, $162, and $186 for Jersey bulls, respectively
RESULTS (continued)
How many different sires of young AI bulls are there?
Holstein Jersey
Number of sires
OBJECTIVES
To investigate the effects of increased usage of young bulls on:
Change in generation interval
Percentage of sons sired by young bulls
Percentage of breedings to young bulls
Average genetic merit of young bulls
Young bull birth year
Who are the sires of sons?
Birth year of sons
Holstein
Jersey
Count of sons
Percent of sons
sired by young bulls
Young
First crop
Old
2008
3,193
16,191
8,585 13
321
1,653
854
2009
2,974
14,692
7,942
388
1,714
985 14
2010
6,167
13,296
4,824 34
812
1,768
696 33
2011
9,904
12,795
3,469 61
1,051
1,715
421 49
DATA & METHODS
Pedigree data was obtained from the US national dairy database (USDA; Beltsville, MD)
Service sire age groupings included: young (0.8 to 3.9 year), first crop (4.0 to 7.9 year) and old bulls (≥8.0 year)
Sire status and lifetime net merit from the USDA official December 2011 genetic evaluation
US breeding records from 2007 through 2011, 19,359,730 Holstein and 1,133,090 Jersey breedings, were examined
What is the genetic merit for Active (A) and Genotyped (G) bulls?
What is the distribution of service sire age in breeding programs?
Holstein Jersey
Percent of total breedings
RESULTS
How has the generation interval changed with genomics?
CONCLUSION
Use of young bulls has greatly reduced the generation interval and improved the rate of genetic gain since implementation of genomic evaluations.
Breeding year
What is the average genetic merit for active and genotyped bulls?
Average age (year)
Birth year
Holstein
Jersey
Sire
Dam
Males
2006
7.1
4.5
6.8
3.8
2011
5.2
4.0
5.8
3.6
Females
7.0
4.9
6.3
5.7
4.6
6.0
Holstein Jersey
REFERENCES
Olson, K. M., J. L. Hutchison, P. M. VanRaden, and H. D. Norman Changes in the use of young bulls. J. Dairy Sci. 94, E-Suppl. 1:27 (Abstr.).
VanRaden, P. M., K. M. Olson, G. R. Wiggans, J. B. Cole, and M. E. Tooker Genomic inbreedings and relationships among Holsteins, Jerseys, and Brown Swiss. J. Dairy Sci. 94:
Net Merit ($)
Breeding year